封育对伊犁绢蒿荒漠草地土壤碳氮磷、酶活性及其化学计量特征的影响OA北大核心CSTPCD

It is important to determine the changes in soil enzyme activity and enzyme stoichiometry during grazing exclusion to understand how vegetation restoration affects soil nutrient availability,and to elucidate the mechanisms of nutrient cycling in ecosystems. In this study,therefore,the responses of soil in sagebrush desert grassland to 6 years of grazing exclusion were initially analyzed by measuring soil carbon (C),nitrogen (N) and phosphorus (P) contents,as well as soil enzyme activities and their stoichiometry. The results showed that:1) There were no significant changes in soil organic C,total N,and total P contents,soil C/P,soil N/P,soil leucine aminopeptidase,alkaline phosphatase activities and soil enzyme C/N,in the 0-20 cm soil layer after grazing exclusion. The activities of β-1,4-glucosidase in April and β-1,4-N-acetylglucosaminidase in July Manasi showed an increasing trend,compared with those in the control,after grazing exclusion;2) Grazing exclusion significantly affected the soil C/N in July Manasi,increased soil enzyme C/P in April,and decreased soil enzyme N/P values in July Manasi. In a vector analysis,the vector lengths of all samples increased significantly in April after grazing exclusion,and the vector lengths of all samples before and after grazing exclusion were greater than 45°,suggesting that the soil microorganisms in the study area were mainly limited by C and P;3) The results of a redundancy analysis showed that soil C,N,and P contents and their stoichiometric characteristics explained 56.03％ of the variance in soil enzyme activity and stoichiometric and vector characteristics after grazing exclusion. These results indicate that soil organic C content may be the main factor influencing the activity of soil enzymes and their characteristics in sagebrush desert grasslands.